No abstract

The hypothesis tested was that inhibition of the L-arginine-nitric oxide (NO) pathway may represent a potential central mechanism of action for acetaminophen (paracetamol). Spinal administration of N-methyl-D-aspartate (NMDA, 0.5 nmol), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA, 0.1 nmol) or substance P (SP, 0.5 nmol) to the rat provoked a specific behaviour characterized by biting, scratching and licking (BSL). This behaviour was antagonized by pretreatment with acetaminophen for NMDA and SP but not for AMPA. Further, the antinociceptive effect of acetaminophen was readily reversed by administration of the natural substrate for nitric oxide synthase (NOS), L-arginine, but not by D-arginine. This suggests that the analgesic effect of acetaminophen is related to inhibition of NO generation. Potential mechanisms for this may involve NMDA and SP. Our data suggest that a significant portion of the analgesic effect of acetaminophen, when used clinically, may be related to an interaction with the central nervous system L-arginine-NO pathway.

No abstract

The aim of the present study was to assess the efficacy and tolerability of single oral doses of 50 mg and 100 mg of diclofenac-K compared to placebo in migraine sufferers during three attacks. The study was conducted in a double-blind, randomized, placebo-controlled, three-period, within-patient comparative trial; 72 migraine patients were treated with diclofenac-K (50 mg or 100 mg) or placebo at six centres (1 in Sweden and 5 in Finland). The primary efficacy end-point was the change in pain intensity assessed on a 100 mm Visual Analogue Scale (VAS) at 120 min after taking the study medication. We found that 50 mg and 100 mg of diclofenac-K reduced the pain intensity significantly better than placebo (p = 0.003 and p = 0.001, respectively), without difference between the doses; 100 mg diclofenac-K was significantly better than placebo in improving phonophobia, photophobia, working ability and need for rescue medication. Diclofenac-K 50 mg or 100 mg is an effective and well-tolerated acute treatment for migraine headache and its associated symptoms. The higher dose of diclofenac-K was only marginally more effective than the lower dose.